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| [[Image:1kwc.jpg|left|200px]] | | {{Seed}} |
| | [[Image:1kwc.png|left|200px]] |
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| {{STRUCTURE_1kwc| PDB=1kwc | SCENE= }} | | {{STRUCTURE_1kwc| PDB=1kwc | SCENE= }} |
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| '''The His145Ala mutant of 2,3-dihydroxybiphenyl dioxygenase in complex with 2,3-dihydroxybiphenyl'''
| | ===The His145Ala mutant of 2,3-dihydroxybiphenyl dioxygenase in complex with 2,3-dihydroxybiphenyl=== |
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| ==Overview==
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| BphC derived from Pseudomonas sp. strain KKS102 is an extradiol-cleaving catecholic dioxygenase. This enzyme contains a non-heme iron atom and plays an important role in degrading biphenyl/polychlorinated biphenyls (PCBs) in the microbe. To elucidate detailed structures of BphC reaction intermediates, crystal structures of the substrate-free form, the BphC-substrate complex, and the BphC-substrate-NO (nitric oxide) complex were determined. These crystal structures revealed (1) the binding site of the O(2) molecule in the coordination sphere and (2) conformational changes of His194 during the catalytic reaction. On the basis of these findings, we propose a catalytic mechanism for the extradiol-cleaving catecholic dioxygenase in which His194 seems to play three distinct roles. At the early stage of the catalytic reaction, His194 appears to act as a catalytic base, which likely deprotonates the hydroxyl group of the substrate. At the next stage, the protonated His194 seems to stabilize a negative charge on the O2 molecule located in the hydrophobic O2-binding cavity. Finally, protonated His194 seems to function as a proton donor, whose existence has been proposed.
| | The line below this paragraph, {{ABSTRACT_PUBMED_12206778}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12206778 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_12206778}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Uragami, Y.]] | | [[Category: Uragami, Y.]] |
| [[Category: Four time repetitions of the beta-alpha-beta-beta-beta motif]] | | [[Category: Four time repetitions of the beta-alpha-beta-beta-beta motif]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 23:14:53 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 11:08:45 2008'' |